The present invention relates to liquid crystal displays and, more particularly, to a novel liquid crystal display having a partially-transmissive reflective transflective member and means for imparting the proper polarization to unpolarized light from a source for transmission through the transflective member for lighting the display in low ambient light situations.
Known liquid crystal displays have the advantage of operating at low power levels and being visible in high ambient brightness environments. One such display typical of the type is disclosed in pending U.S. application No. 667,270, filed Mar. 15, 1976 and assigned to the assignee of the present invention and now abandoned. The "Reflective Dichoric Display" disclosed therein utilizes a liquid crystal cell of the twisted nematic type and having a suitable dichroic dye dissolved in a liquid crystal material. The cell linerarly polarizes incident unpolarized ambient light (in the quiescent state with a positive anisotropy liquid crystal material). The cell is backed by a quarter-wave plate and a reflective means, whereby light is absorbed in the display in a quiescent mode and is reflected by the display in an active mode. Proper operation a display of this type requires ambient light of sufficient magnitude to allow indicia, formed by the display, to be visible at the magnitude of light reflected by the display. In low ambient light situations, the magnitude of the somewhat attenuated reflected light is insufficient for normal viewing. A liquid crystal display having the desirable high contrast of such a liquid crystal display, but viewable in both high and low ambient lighting environments is desirable.